1. Field of the Invention
The invention relates to an air pump, and more particularly to an air pump which decreases manufacturing elements and is easy in assembling.
2. Description of Related Art
With reference to FIGS. 8 and 9, an air pump comprises a body 60, a piston rod 70 and a seal cap assembly 80. The body 60 is hollow and has a top surface, a bottom surface, an outer surface, an inner surface, an opening 61, a nozzle 62 and multiple concave loops 63. The opening is formed in the top surface of the body 60. The nozzle 62 is mounted on the bottom surface of the body 60. The concave loops 63 are formed in the inner surface of the body 60 near the opening 61 of the body 60.
The piston rod 70 is inserted into the body 60 and has a piston 71. The piston 71 is mounted on an end of the piston rod 70 and is located in the body 60.
The seal cap assembly 80 has a plug 81 and a collar 82. The plug 81 is movably mounted on the piston rod 70 and has multiple convex ribs 83. The convex ribs 83 are respectively received in the concave loops 63 of the body 60. When the piston rod 70 is pressed into the body 60 via the opening 61, each convex rib 83 is engaged with one of the concave loops 63. The collar 82 is mounted on the body 60 and outside the outer surface of the body 60 near the opening 61 of the body 60. The collar 82 has a flange 84. The flange 84 protrudes inward from the collar 82 and is mounted between the top surface of the body 60 and the plug 81.
After the plug 81 is fixedly engaged in the opening 61 of the body 60, a gap is formed between the plug 81 and the top surface of the body 60. Thus, the air pump needs the collar 82 to close the gap. The flange 84 of the collar 82 is just mounted between the top surface of the body 60 and the plug 81 and is not fixed, so this may cause the relative rotation between the collar 82 and the body 60. The relative rotation between the collar 82 and the body 60 may be considered as a defect of the air pump in that the plug 81 that is not sealed tightly. Then, the stores selling the air pump have the problems of having to refund customers and suffer damage to the reputation as a supplier of goods.
To overcome the shortcomings, the present invention provides an air pump obviate the aforementioned problems.